Getting the Most out of the D3.js Documentation

The D3 docs are one of the best ways to solve a problem you are encountering and learn about areas in D3 that you were unaware of. This post explains the basic conventions that are used in the D3 documentation. Let’s look at three examples from the API.

d3.selectAll(selector)

In this example, the selectAll method is being explained.
Notice that the selectAll method is attached to the d3 namespace. If the method being explained is not
attached to the d3 namespace, the object it is attached to will be specified. The italicized word (selector in this case) is a description of the parameter
passed to the method.

selection.property(name[, value])

While it might look like an array, parameters inside brackets (value in this case) signify an optional parameter. The comma included inside the bracket reinforces that idea.

d3.csv(url[[, row], callback])

Here we have a required parameter url and two optional parameters accessor and callback. In this case, if you provide two parameters to the .csv method, they will be the url and the callback. However, if you provide 3 parameters, the second will be the accessor parameter, not the callback parameter.

Understand what’s actually happening

You will inevitably get stuck as you get better at D3. Get into the habit of going to the docs first. Make sure you understand the purpose of the methods you trying to use. You might be surprised to find that these methods are more powerful then you expected.

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